AMZ MOSFET BOOSTER ISSUE

[harrisxr650]

hey guys.
i'm running a annoying issue with a jack ormans amz mosfet booster built on vero.
i'm using a verified layout which i've build several times , i'm getting static noise and crackles when engaged, i'm using shielded cables for input and output, all components are tested witn dmm before soldered, the pot its active on all its range and can here the boosted signal as it should be but with static noise, all joints are fine, jacks and 3pdt as well, running from new 9v battery away from other electronic devices, changed the transistor (BS170) 4 times with no luck... and made new board 4 times as well with new components,
because i'm not having an amp here i'm testing with sound card and guitar rig( but away from pc)
the layout can be found on the page below ( scroll down to the middle of the page).
any help will be appreciated.
thanks

[GibsonGM]

Did you make sure of the pinout on the mosfet?  Are they from a 'good manufacturer'?   Shielded cables only grounded at one end, and not touching signal conductor in ANY way?     Any electrolytic caps put in backwards?   Could something be touching the grounded enclosure?  Enclosure-cramping is a major source of problems, so does it work when NOT in the box?

Any chance you could have static-popped them in handling?    Are you using a protection Zener, and is it oriented the right way?

Does gently moving wires around change the static?

Could be something shorting against something else...sounds like one of those deals where you have to look at all your solder joints with a magnifying glass and bright light, and do this several times.  PITA, but it happens....

This is my go-to booster, and it's flawless when built well - we often make mistakes we don't catch, but if you keep looking you'll probably find out what it is. 

[harrisxr650]

pinout is correct, manufacturer unkown, bought them from banzai.com, tried with 2n3904 and 2n5088 as well with no luck, shielded cables grounded only  at one end and not touching anything, caps are correct oriented, nothing is touching the enclosure, works outside the box with the same issue, zener is correct oriented,
moving cables doesnt affect static,
i've build many these and never had that issue...  i did a reflow on all joints with no luck... maybe if i use my probe to check where the static noise occurs in the signal path? could it be dc in the signal path
i;m using this vero layout but its 100% correct , i've build it more than 10 times

http://i272.photobucket.com/albums/jj162/harrisxr650/booster%20buffer.jpg

[GibsonGM]

Well, the 3904 & 5088 won't work as they're BJTs and not mosfets - different biasing arrangement is required to get them working.

Since you've got some signal, the mosfet is probably working, I'd gather.    Yes, an audio probe would be invaluable in seeing what's going on!

Troubleshooting is about eliminating trouble spots...like a bad guitar cable, miswired or shorting jacks (esp. the power jack)...step by step.

Establish that your input signal is clean at the first cap.   Post the voltages present on Q1, too.  Yes, it could be DC in the signal path - bad cap would cause that...audio probing could give you an area to look.   A bad pot could make noise - is it new?  I'd expect it to change the noise when rotated, tho...

It's generally (always?) OUR fault when something proven doesn't work    Little hair of a wire touching where it shouldn't (esp. on switches, you have the LED there to conveniently give you an error...), a track not cut enough and shorting... 

[midwayfair]

Well, the 3904 & 5088 won't work as they're BJTs and not mosfets - different biasing arrangement is required to get them working.

They'll work. They won't sound perfect, but they'll work just fine. It's actually a decent way of ensuring that all the MOSFETs aren't dead.

Op, post pictures of both sides of your board. Use your multimeter's continuity tester, against an actual schematic (not layout) and make sure nothing's connecting to something it shouldn't be. And post your voltages.

[GibsonGM]

^  My bad - never heard of that!    Guess if you stop and think about it, there's no reason why not.   Good tip.

[harrisxr650]

ok...got back from work a while ago and decide to check voltages, shorts and why not rebuild the thing one more time...
well this is embarrassing...turned on my solder station and noticed its on 250C (480F almost)...thought i lower the temp yesterday accidentally while cleaning the mess in my work-desk ... so i put it in 350C  and re flow one of the non working boards...guess what... then i did a reflow on  all 4 i've made...guess what again... no static no cracks amz mosfet booster as it should work...
so sorry guys  for wasting your time and thanks for trying to help...

[GibsonGM]

You learned something.  I did too (about subbing BJT's for a mosfet like this to test!)

So there was no waste of time    Glad it worked out!    See - user error!  Happens to us all!